Commercial NAS RAID1 disks moved to Software Raid system?

Question

I've got a couple of commercial NAS boxes and I'm wondering if they (ReadyNas duo, DLink DNS-323) or any other NAS is suitable for having their RAIDed disks moved to a software-based NAS. To be specific, I'm a big fan of the (largely) Debian-based Ubuntu. Can the aforementioned NAS drives be migrated to Ubuntu (e.g. using the mdadm Linux command)?

Secondly, is there any commercial NAS that can be migrated over? Incidentally, here is a link to somebody who succeeded in a migration: http://www.linuxquestions.org/questions/slackware-14/moving-raid1-drives-into-computer-with-same-md-numbers-862312/

My specific scenario I'd like to prepare for, is the eventual (sudden) death of one of the NAS motherboards.

Answer 1

Based on some poking around my DNS-323, I'd say there is a pretty good chance the md array would work if the disks were hooked up to another linux box. My array is made from two 'regular' linux partitions:

/ # uname -a
Linux NAS-01 2.6.12.6-arm1 #32 Wed Jun 24 15:19:48 CST 2009 armv5tejl GNU/Linux
/ #
/ # df -h
Filesystem            Size  Used Avail Use% Mounted on
%root%                9.7M  7.9M  1.3M  86% /
/dev/ram0             9.7M  7.9M  1.3M  86% /
/image.cfs            5.7M  5.7M     0 100% /sys/crfs
/dev/md0              1.4T  147G  1.2T  11% /mnt/HD_a2
/dev/sda4             487M   11M  476M   3% /mnt/HD_a4
/dev/sdb4             487M   11M  476M   3% /mnt/HD_b4
/ #
/ # fdisk /dev/sda

The number of cylinders for this disk is set to 182401.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/sda: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1          66      530113+  82  Linux swap / Solaris
/dev/sda2             131      182236  1462766445   83  Linux
/dev/sda4              67         130      514080   83  Linux

sdb is identical, but the 'raid' partition types (sda2 and sdb2) are 83 and not linux raid autodetect (fd), which is perfectly legit.

I have funplug installed on my DNS-323, which gives me more of the standard Linux commands to play with but note that the default fdisk on the system dies with a SEGFAULT and so you have to install a replacement, as per this forum post, to get a working copy:

http://www.consumedconsumer.org/2010/06/upgrading-my-dns-323-to-2-x-2-tb-ii_08.html

As you can see (below), the raid array is pretty standard:

/ # cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] 
md0 : active raid1 sda2[0] sdb2[1]
      1462766336 blocks [2/2] [UU]

unused devices: <none>

I'm not going to pull out these disks and try them in my linux server (spoilsport, I know ;-) ), but I'd say the chances of them 'just working' (even with a minor bit of fiddling with mdadm and fdisk) are high.

Answer 2

Some hardware NAS boxes use Linux (or for example some BSD variant). In that case there is high probability for compatibility with Debian.

It's hard to say about those specific devices without owning those. Easiest way is to try it, before you are in problem. If it's not possible, you can start making better backups. :)

DNS-323 runs Linux, see for example this page. Most probably it is using standard RAID1, but I couldn't find facts from Internet.

ReadyNas Duo uses Linux. In ReadyNas Duo disks there should be Linux partitions in the beginning, and then RAID space. Most probably that works in Linux directly.